OneRotor

iTrader: (3)

alright, you read my post and responded while i was editing it. i fixed the newton's law statement, it's the thrid law. this law has everything to do with an engine, because every action has an equal and opposite reaction, think about it, you increase the volume in a cylinder with a moveable piston and the piston will move to keep the pressure constant. you're right, i don't have the authority to speak as an expert, but for once, will you look at the damn site. just because it's not in your textbook DOESN'T mean that it's not possible. the guy in New Zeland is a professor, and he is currently working on getting it running. U of M, figures, i'll keep my views on the engineering department to myself, because this isn't about my views on your school of choice, it's about the hydrogen rotary engine. look at the link and see where i'm coming from. i'm quoting that site, don't tear me apart for letting you know what people are working on.

oh, and water injection into a turbocharged engine is used to cool the intake charge. i'm talking about a completely different idea.

open your mind to new ideas. this is why i refused to go to U of M for engineering, they drill formulas and definations and everything into your head, so your are extremely smart when it comes to these aspects, but you can't think for yourselves, you can't open your mind to new ideas. if your textbook says it can't be done, then it can't be done, that's what i've gotten from what i've heard from people who go to the U, along with numerous people who work in the automotive industry.

Hamza734

Kid, you got a lot to learn....

I DID look at that site. It's funny, I didn't happen to notice that he had a functioning prototype. Or even a picture of the engine. Until he produces a working prototype, his idea is nothing but speculation.

Yes, it IT completely different. Your talking about an engine powered by water vapor. I'm talking about an engine powered by gasoline.


Last year Michigan was rated number 2 in ME. Where exactly was Michigan Tech? And while we're comparing, how did MTU's Formula SAE car fare last year? Did it beat Michigan? Hell no. What about 2002? Not even close. When your researching an idea, the first thing you do is check the literature. If their's no reference to your desired research, that should tell you something.

Frankly, I think your lying. The most open-minded engineers I've met have been at Michigan. There's 10x more cutting edge research at Michigan then there is at MTU. I won't waste any more time arguing with fools. Your technical arguments have no merit and your comment on Michigan are flat wrong (jelous are we? ). Once you have some idea what your talking about, then we can talk...

OneRotor

iTrader: (3)

we're not talking about the FSAE team, or where schools are rated. if i understand correctly about why we're not rated high is because we're on 15 week semesters, and all of the top schools are on 14 week semesters, so our curriclum isn't as demanding. this is why we're switching to 14 week semesters next year, so we can be up in the running with the top schools.

and about me lying, i've talked to engineers at Bosch, Eaton, Ford, and Visteon, and all of them said if they had to choose between 2 people applying for the same job, that had the exact same qualifications coming out of college, same GPA, same extra curricular activities (like FSAE or Mini Baja or Clean Snowmobile), and one was from U of M and the other was from MTU, they all said that they'd hire the person that went to MTU because U of M teaches all theory, and on tests, the students from U of M will do better than 90% of all Tech students, but when it comes to applying everything that they had learned, the person applying that went to Tech would know how to use what they have learned right out of the box, while the person that went to U of M would take a while to get the hang of doing everything. yes, U of M has a better engineering program from the book standpoint, but Tech has a more hands-on approach, and this IS NOT my opinion, it's information that i've gotten from engineers at major corporations.

now, it may seem a little far fetched, but forget your theories for one second and think about the concept behind the way an engine runs. air and fuel are drawn in, compressed, ignited, and the expanding gas puts pressure on the rotor, which causes it to turn and spin the EC.
the concept behind the engine that the professor in New Zeland is the exact same, except instead of using an air/fuel mixture to produce the pressure to spin the rotor, he's using the air/fuel mix to heat the combustion chamber, and then he injects water which expands (exactly the same way that the air/fuel mix expands in a normal engine), causing pressure (just like the expanding burning mixture of air and fuel), which in turn causes the rotor to spin (just like with an air/fuel mix), turns the EC and creates power. you're right, he doesn't have a working prototype, but the concpet makes complete sense.

Hamza734

I seriously doubt one week makes a difference in ratings.....

I still think your lying about companies preferring MTU. If that's the case, why is the average salary of Michigan grad higher then a MTU grad? If MTU is such a great "hands-on" school, why did MTU place far behind U of M in FSAE, Solar Car and Mini Baja? Just stop making excuses....All my ascertations are backed up with facts, everything you say is backed up by heresay.

As to the technical matter, I'll concede-virtually anything can be used as a working fluid. The point is, water is NOT an ideal fluid.

Hamza734

As a little aside, let me share the experience of my father. He taught ME at a school (Lawrence Technical University) whose raison d'etre is practical experience. Every student is required to work in an engineering related field during their entire time of study. He'll tell you the same thing I will: "Michigan is vastly better in both theory and practice!"

OneRotor

iTrader: (3)

i was on the FSAE team for a couple of months at the beginning of the year, i couldn't continue with the project because i couldn't get to the meetings (broke my foot running) or get into the shop. the reason why U of M did better than MTU in FSAE is because the tech FSAE team is run horribly. nothing is scheduled, everyone is running in different directions. i found that it was a miracle that they even had a car running. another problem with the tech FSAE car is that it wouldn't hold together through anything. i watched them spin it during a test run, and the whole left front hub, brake assembly, everything came detached from the suspension arms. that is probably why the U of M team did better, because A. they are probably more organized, and B. because their car held together, two things that the Tech team can't seem to get. with the Mini Baja and Solar Car, i can't speak for them, because i have no clue why they didn't win.

as far as the water/hydrogen idea, that's all i wanted was for you to agree that it is possible to power a car like that. it may not be efficient, or run very well, but it is possible, and i wanted to put information out for people to know what people are working on for the future of the rotary engine

OneRotor

iTrader: (3)

apparently, the school thinks that it will up our standings, because they will stuff the same amount of information into one less week, which will make us have to study harder and work under more stress. the university thinks it'll make a difference, but only time will tell.

Kenku

Okay, I went and looked at the water/hydrogen page. It's not all that bad of an idea, honestly... it's using water to leverage hydrogen's higher heating value. Using the high chamber temperature to superheat water into high pressure steam should generate a much higher pressure system than just burning hydrogen, which is a lot easier to convert into mechanical work. In theory, it should work. Maybe. I say that without going and running any numbers; this is sort of a reminder to myself to look at some things after my materials final.

Now, all inter-state university pissing contest aside, it doesn't really sound like either of you have much of an idea what you're talking about. See if you can figure out who I'm talking about below.

On one side of the argument, Newton's laws of motion aren't really applicable to this. You can model it as a completely stationary system. Also, the Powerballs etc aren't ways of generating hydrogen, per se. They're ways of storing hydrogen in a medium such that it's easily transportable. You still need to do electrolysis at one end to get the hydrogen to bond with whichever chemical. Oh, and also, your comments about bore vs. stroke sort of contradict each other if you look at them.

On the other side of the argument, if you can't figure out how you can get a high-pressure volume by superheating water, you have no business having a bachelor's degree! Good god.


Okay. Homework time. Show work and state any additional assumptions that are necessecary.

Given the assumptions of a 1L cylinder with a 10:1 compression ratio, 100% volumetric efficiency, starting temperature of 30*C, starting pressure of 100kPa, gasoline's heating value of 47.3mJ/kg, gasoline's 14.7:1 air/fuel ratio by mass, hydrogen's heating value of 141.6mJ/kg, hydrogen's stoichiometric ratio of 27.2:1 by mass, and an adiabatic process in all cases. Find the peak pressure from burning gasoline. Now, in the same cylinder, calculate peak pressure by burning hydrogen.

Finally, and this is the relevant one, given a cylinder pressure after hydrogen combustion of 10mPa (semi-arbitrary; diesel injection can be in the neighborhood of 20mPa so 10 seems safe) calculate the maximum amount of water that can be injected while still having enough energy from hydrogen combustion to convert all of it to superheated vapor... and the peak pressure from doing so. The amount of hydrogen will likely be smaller than the previous problem, and the upper limit of water that can be injected is equal to the cylinder's clearance volume (though I doubt that will come into play)

Extra credit: Calculate the amount of water needed to be converted to superheated vapor to equal the peak pressure produced by burning gasoline, and the amount of hydrogen that needs to be burned to produce enough energy to vaporize it. If you want, calculate what volume of fuel will have to be stored per cycle.



Now, if someone goes and works all that **** out, I think we can say once and for all whether it's a stupid concept or not. You should be able to do this stuff without too much trouble, but if noone manages/bothers to by this weekend I'll do it myself. If neither of you can figure this out, then just admit that you don't know how well it would work.

OneRotor

iTrader: (3)

good god you know alot of stuff, do you know all of the heating values and stoichiometric ratios by heart, or did you have to look them up? because if you knew those right off hand, that amazes me. i'll work on this, can't gaurauntee that i'll get any answers (or correct ones at least), it'll take a while because i'm going to do this while i take breaks from studying for the finals i have next week. thanks for the information to figure out whether this would be a good idea or just a theory.

one question for you though, when you said mPa, did you mean milli-Pascals, or mega-Pascals? i know that the prefix "m" means milli, but i want to know which one you want us to use, because that would change our answers dramatically

Kenku

Heh, my bad... mega-Pascals. Something was nagging me about the lowercase m but...

Didn't know the heating values offhand *exactly* but I've got reference books handy.

*shrug* Like I said, just got kinda pissy about how it was turning into an argument that had nothing to do with the validity of the concept. I may just be getting cranky in my old (joke; I'm 22) age.

OneRotor

iTrader: (3)

haha, alright, thanks for clarifying it, i'll work on it, can't gaurauntee that i'll get anything right, but i'll hack at it.

Doubleohsmurf

nice diffuse, lol

Adam

ok so mazda came out with 3 rotor engine! why not goto 5! thats three more than mine! making oh maybe 700 hp!

KevinK2

you missed my 1.3 factor (1.3 x your 1.5 = my 2). rotor applies force directly to crank pin. neglecting friction, the pin-to-pin force in the conrod is higher than the force applied by the piston, due to the rod angle (I assumed 40 deg from vertical). So 2x more peak torque, assuming same pressure at that time.

in theory, same energy delivered per rev. energy = volume change x ave pressure, as I posted before. may be peak torque is a factor, or something else, but the 2.5L 944 I drove had more low end pull than the 13B na I drove, at same rpms.

MikeC

Hi Kevin,

Interesting point, I'd never realised the rod angle caused so much difference. However, if you summed up the torque produced over a single expansion the rotary would produce 1.5 times less. As you stated, the work is the same but the distance is 1.5 times longer (270vs180), so the torque must average out to 1.5 times less. You wouldn't feel the 2x torque because it would be a short peak. I wonder which is preferable for performance, the piston motor would produce a greater leverage length but expand through the early stages quicker and spend more time in the later part of the stroke, the rotary would have less leverage but spend more time in the earlier part of the stroke.

BTW, did you this thread? I've updated it to include your spinning radial piston engine except with 3 cylinders instead of 4. The current version doesn't have this yet because I need to finish a couple of things off before releasing the update but it should be out soon. It looks very interesting seeing it spinning around next to the rotary.

https://www.rx7club.com/showthread.p...e&pagenumber=1

Cheers,
Michael

KevinK2

yup, nice work. had fun with the multi-lobe designer.
rotors with 5, 7, 9 etc faces could use multiple (but shared) exh, intake, and ign stations on the housing. but Looks like anyting over 3 has geometric interference.

I would suggest a crank angle range bar consistent with one chamber cycle, more informative vs rotor rotation? The spinning 3 pistion sounds great.

torque .... would be nice to find torque curves for the 944 and 13B na.

MikeC

In all cases you can get the design to be at least workable, as the number of faces goes up the eccentricity needs to go down. Playing around with that screen it became pretty obvious why the chose the design they did.

I'm not sure what you mean?

Here's the latest version, there might be a few bugs. I just need to add a few more help topics as the radial piston engine won't make much sense without it.

http://mikesdriveway.com/engineapp/e...pp20040516.zip

The similarities between the radial piston motor and the rotary are quite interesting, both have 270 degree expansion, fire each rev, produce 1.5 times less torque, rev 1.5 times higher, have the same piston/rotor face surface area, take 3 revs to complete a cylce, have a swept volume per chamber of 654ccs, suck 2.6 litres of air per 2 revs and the volumes in the chambers are always equal (if you ignore the minor difference due to rod angle).

jhillyer

That's like saying your clan is doomed because of the shape of you and your daddy's skull, that evolution stands no chance in correcting it's abominations. I think a group of sharp medical engineers can grasp your skull and find ways to improve it.

jhillyer

The pin-to-pin force is equal, and the piston face shares this load. The torque becomes multiplied across the crank arm as one aproaches the crankshaft axis.

Very unlike the piston, the NSU Mazda rotary has a crank-moment extending from crank shaft axis beyond its arm (lobe) until the apex seal. The arm moment is quite long for several degrees of rotation. I agree, though, that without radical geometry changes, it can't get "stroked" easily like a piston.

neptuneRX

I like eurobeat

MikeC

That's not true, the level length for the rotary peeks at 15mm, which is quite a short lever. It's compensated by having a 14560mm2 surface area which equates to something like a 136mm bore.

jhillyer

That's a cannon bore!
Which portion am I confused about?

I'll be clear that I'm not refuting, and I'm being careful not to encourage the same.

What I'm viewing is a major length of the rotor face involved in leveraging the crank.

I see that a large portion of the rotor face is partially pressed through the crank, with a minor portion opposing, wasted much like piston force near top-dead. Yes the total arm from crank center to apex seal is quite short.

MikeC

I had a long conversation about this a while ago and this is the is the description that came out at the end of it:

If you imagine 2 people holding up a horizontal plank of wood on their shoulders and one guy is standing dead in the middle of the plank of wood, how much weight is the other guy holding? The guy in the middle is holding all of the weight and the other guy is holding none, no matter where he stands or how hard he tries to hold some of the weight he can't.

It's the same with the rotary, assuming the pressure is evenly spaced across the rotor face during combustion the eccentric shaft takes all of the weight and the stat gear takes none. So the force acts through the centre of the eccentric shaft lobe at a maximum moment of 15mm. Have a look at this diagram.

http://www.mikesdriveway.com/misc/rotortorque.jpg

It makes sense that the lever arm is quite small (compared to a piston motor) because the rotor face surface area is so big.